Apparatus for creating duplex reproductions

ABSTRACT

A DUPLEXING METHOD AND APPARATUS FOR PRODUCING DUPLICATE REPRODUCTIONS OF ORIGINAL SUBJECT MATTER ON OPPOSITE SURFACES OF A SUPPORT MATERIAL. TWO OPPOSITELY READING LATENT ELECTROSATIC IMAGES OF SUBJECT MATTER TO BE REPRODUCED ARE CREATED ON A PHOTOSENSITIVE SURFACE AND ARE DEVELOPED WITH DEVELOPER MATERIAL WHEREIN ONE OF THE IMAGES COMPRISES A RIGHT READING IMAGE WHICH IS TRANSFERRED TO STORAGE MEDIUM AFTER DEVELOPMENT. THE OTHER IMAGE BEING IN WRONG READING OR MIRROR FORM REMAINS ON THE PHOTOSENSITIVE SURFACE TO BE DIRECTLY TRANSFERRED THEREFROM IN ONE SIDE OF A SUPPORT MATERIAL WHEREUPON THE DEVELOPED IMAGE RETAINED ON THE STORAGE MEDIUM IS TRANSFERRED TO THE OTHER SIDE OF THE SUPPORT MATERIAL TO CREATE A DUPLEX REPRODUCTION.

June 20, 1972 J. FANTUZZO ErAL 3,671,118

APPARATUS FOR CREATING DUPLEX REPRODUCTIONS Filed Dec. 24, 1969INVENTORS JOSEPH FANTUZZQ FRAZER D. PUNNETT BY A 7' TORNE Y UnitedStates Patent Oflice 3,671,118 Patented June 20, 1972 US. Cl. 355-3 7Claims ABSTRACT OF THE DISCLOSURE A duplexing method and apparatus forproducing duplicate reproductions of original subject matter on oppositesurfaces of a support material. Two oppositely reading latentelectrostatic images of subject matter to be reproduced are created on aphotosensitive surface and are developed with developer material whereinone of the images comprises a right reading image which is transferredto a storage medium after development. The other image being in wrongreading or mirror form remains on the photosensitive surface to bedirectly transferred therefrom to one side of a support materialwhereupon the developed image retained on the storage medium istransferred to the other side of the support material to create a duplexreproduction.

BACKGROUND OF THE INVENTION This invention relates in general toproducing reproductions of subject matter and, in particular, to animproved method and apparatus for producing duplicate reproductions ontwo opposite surfaces of a support material.

More specifically, this invention relates to a duplex method andapparatus wherein a right reading latent electrostatic image of subjectmatter to be reproduced is formed and developed on a photosensitivesurface and is transferred therefrom to a storage medium to be retainedthereon. A second wrong reading or mirror latent image is also formedand developed on the photosensitive surface and is transferred directlyto one surface of a support material at a transfer station. The othersurface of the support material receives through transfer the developedimage retained by the storage medium to produce a duplex reproduction ofthe original.

Although not intended to be so limited, the duplexing method andapparatus of the present invention is described for convenience ofillustration in conjunction with the xerographic technique ofreproduction. In the process of xerography, a xerographic surfacecomprising a layer of photoconductive material on a conductive backingis given a uniform electric charge on the surface and then is exposed tothe subject matter to be reproduced by various projection techniques.This exposure discharges the surface in accordance with the lightintensity reaching it thereby creating a latent electrostatic image onor in the surface. Development of the image is effected by developerswhich may comprise, in general, a mixture of suitable, pigmented ordyed, resin base powder, hereinafter referred to as toner, which isbrought into contact with the surface by various Well-known developmenttechniques. During such development of the image, the toner powder isbrought into surface contact with a photoconductive coating and is heldthere electrostatically in a pattern corresponding to the latentelectrostatic image. Thereafter, the developed xerographic image may betransferred to a support material to which it may be afiixed by anysuitable means such as heat fusing.

Numerous methods and appaartus have been employed in the prior art toaccomplish the aforementioned basic process of xerography, but generallythese prior art reproductions have been limited by the fact that onlyone surface of a support material is utilized to create a duplicatecopy. Such an employment of but one surface of a support material toreceive developed toner images is uneconomical since a greater amount ofsupport material is required because it requires approximately twice theamount of support material as needed by duplex duplicates. Further,duplex reproductions result in convenient to use duplicates because theymay be readily assembled in book form which is especially desirable ifan original document includes a large quantity of sheets or the like tobe reproduced. Also, since the number of sheets required for duplexreproductions is much less than utilizing only one side of the supportmaterial, a great economy of physical volume of the reproductionsresults to alleviate the problems of storage of the copies for futureuse. Therefore, it is advantageous in xerography to provide aninexpensive and eflicient method and apparatus for producing duplexreproductions of an original document or the like.

One attempt in the prior art to produce a duplex xerographicreproduction of an original is disclosed in the US. Pat. No. 3,318,212to Rubin wherein xerographic reproduction is produced on opposite sidesof a sheet of support material. Although such a system disclosed inRubin provides satisfactory duplex reproductions, it suflers from theproblem of being comparatively complex and requires the use of atackified image to produce a duplex duplicate. The provision of atackified image requires the utilization of a vapor chamber for bothsurfaces from which the toner image is transferred to the supportmaterial. Further, the use of a tackified image does not provide forrapid and high quality production of a duplicate copy as compared to asystem utilizing dry tones images for transfer. Therefore, it isdesirable in xerography to provide an ef fective system which utilizes aminimum of elements and complexity to provide duplex duplicates whenusing a dry toner material.

SUMMARY OF THE INVENTION It is, therefore, an object of this inventionto improve the method and apparatus for producing reproductions oforiginal subject matter.

.Another object of this invention is to improve the method and apparatusfor producing duplex reproductions.

These and other objects are obtained in accordance with the presentinvention wherein there is provided a duplex method and apparatus thateffectively produces reproductions on two sides of a support material.The method and apparatus disclosed herein utilizes a photosensitivesurface whereon two electrostatic latent images of opposite reading arecreated and developed. A right reading latent image is first formed anddeveloped on the surface to be thereupon transferred to an image storagematerial where it is stored until a developed second wrong reading imageon the photoconductor subsequently reaches the transfer station. Then bypassing a sheet of support material past both the photoconductor surfaceand the storage material, each of the respective developed imagesthereon are transferred to opposite sides of the support material.Thereafter, the transferred image lying on both sides of the supportmaterial are transported to a fusing area where a permanent duplexreproduction is produced.

The novel method and apparatus of the present invention producessatisfactory duplex reproductions with a minimum of elements. Theoriginal copy may comprise, for example, a two sided original document,two separate sides from two originals, or a side by side microfilmdocument and the like. The invention requires only one storage mediumand a single photosensitive surface to effect a duplex reproduction ofthe original copy wherein merely one image transfer is necessary besidesthe actual transfers to the support material. Further, the duplex methodand device of the present invention utilizes a dry toner image to betransferred electrostatically to a support material in a manner notheretofore possible because the prior duplex systems require use oftackified images to effect a duplex reproduction. The present systemdisclosed herein results in a faster and more economical device whichreadily produces high quality duplex reproductions with less complexitythan prior art duplex systems.

DESCRIPTION OF THE DRAWING [Further objects of the invention togetherwith additional features contributing thereto and advantages accruingtherefrom will be apparent from the following description of oneembodiment of the invention when read in conjunction with theaccompanying drawings where- FIG. 1 is a schematic illustration of aduplex xerographic reproduction device of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, there isshown a schematic view of a drum type automatic xerographic reproducingmachine for producing duplex reproductions according to the presentinvention. The central element of the apparatus is a drum I mounted forrotation and drivable in a clockwise direction by motor M. The drumcomprises an outer surface with a layer of photoconductive insulatingmaterial such as, for example, vitreous selenium, or any other suitablesurface. A uniform electrostatic charge is placed on the photoconductorsurface of the drum by means of a conventional corona charging device 2.The uniformly charged surface of the drum is then moved to an exposuremeans 3 which exposes the charged surface to copy to be reproduced tothereby form a latent electrostatic image of the copy on thephotoconductor drum surface. The exposure means may comprise, forexample, a device which wil alternately reverse the image of the copy ordocument to be reproduced. Such a reversing image optical system may beany conventional type as, for example, disclosed in the aforementionedUS. Pat. No. 3,318,212 to Rubin wherein microfilm originals are beingduplicated. Other exposure means also may be utilized in conjunctionwith the present invention to expose the drum to alternately readingimages of two sided original documents, one side from two documents andthe like. The optical means exposes the charged surface to copy to bereproduced and forms a first right reading latent electrostatic image onthe photoconductor drum. Following the formation of a right readingelectrostatic image, the image moves past a conventional developmentdevice 4 to bring the latent image into contact with developer material,such as toner powder or other electroscopic material, for developmentthereof.

After development, the visible first right reading image moves to atransfer station -5 which includes a corotron 6 mounted adjacent astorage medium 7 of suitable material such as, for example, a dielectricbelt of Mylar. It is within the scope of the invention to use otherforms and materials for the storage medium such as a drum and the likeor other materials capable of storing a visible toner image. The belt 7is mounted on rollers 8 to allow the surface of the storage medium to bedriven by a suitable motor means (not shown) in direct confrontation tothe surface of the drum 1. A conventional corona device 6 is mounted onthe opposite side of the dielectric belt 7 to transfer the developedright reading image from the drum to the belt by applying an electricalfield to the back thereof.

As is apparent from the foregoing, the visible right reading imagetransferred from the drum thereupon is reversed in reading when placedupon the dielectric material. The length of the dielectric belt may beof any convenient size, such as, for example, one-half the circumferenceof the photoconductor drum. Further, it is desirable to drive the beltat a speed equal to the surface speed of the drum although other speedsof the belt may be selected if desired.

Subsequent to the formation of the first right reading image upon thedrum 1, another area of the surface thereof is uniformly charged by thecorona charging device 2. The uniformly charged surface of the drum thenmoves past the exposure means 3 to expose the surface to additionalsubject matter to be reproduced to form thereon a latent electrostaticimage of opposite reading than the previously formed image which in thisinstance is a mirror or wrong reading image. The latent wrong readingimage on the drum surface thereupon moves to the development device 3 tobring the charged image into contact with developer material to create avisible wrong reading image.

The time sequence of the charging, exposure and development of the twooppositely reading images in the machine disclosed herein is effected bythe machine control circuit (not shown). The particular selected timesequence of operation depends on such factors as the location of variousstations around the drum, the length of and velocity of the storage beltrelative to the size and surface speed of the drum and the like. Forconvenience of illustration the area of the surface of the drum toreceive the first right reading image is located diametrically oppositeto the area of the drum supporting the wrong reading image. Therefore,when the first right reading image reaches the transfer station 5 fortransfer to the storage belt 7 the center of the first image is situatedone-half of the circumference of the drum from the second wrong readingimage. Then by selecting a length of the storage belt 7 of one-half thecircumference of the drum 1 and moving the belt at the speed of drumsurface, the image transferred will move on the belt and return toconfront the transfer station 5 at the instant the visible wrong readinglatent image on the drum moves to the transfer station. Accordingly, thetwo images lying respectively on the storage belt and the drum confronteach other at the same time.

A sheet of support material 9 is delivered to end 7a of the storage belt7 of a conventional sheet feeding mechanism (not shown). Paper tackingcorotrons 10 are mounted adjacent end 7a of the belt on the oppositeside of the roller 7 wherein the sheet of support material is fedbetween the belt and the corotrons 10 and a charge is applied by thecorotrons to the support material to cause the sheet to adhere to thestorage belt directly over the toner image retained thereon. Thereafter,the storage belt carries the sheet to the transfer station 5 and thecorotron 6 applies an electric field to the back of the sheet totransfer the developed image lying on the drum to one surface of thesupport material.

The sheet of support material thereupon retains on one surface thedeveloped image transferred from the drum 1 and the opposite surface ofthe sheet is in contact with the developed image lying on the storagebelt. A second transfer corotron 11 is positioned at end 7b of thestorage belt to apply an electric field to the sheet material as it iscarried by the adherence of the sheet to the belt. The electric fieldproduced by the second transfer corotron 11 transfers the image storedon the belt 7 therefrom to the surface of the sheet 9 of supportmaterial. A conveying means 12 thereafter carries the sheet retaining animage on each surface to a suitable conventional fusing means 13 toafiix the developed image on each surface to the sheet to produce apermanent duplex copy. It should be apparent that the first developedimage stored on the belt creates a right reading toner image on one sideof the support material when transferred thereto. Similarly, the mirrortoner image transfered from the drum to the other side of the supportmaterial likewise creates a right reading toner image and a suitablereading duplex is produced.

In the above description there has been disclosed an improved method andapparatus for effectively creating a duplex reproduction of desiredsubject matter. For convenience of illustration, the exposure meanscreating the alternately reversed images was illustrated as a singlealternately reversing exposure device. However, it should be apparentthat two separate exposure devices may be utilized to optically createeach of the opposite reading images upon the photoconductive drumsequentially or simultaneously. Further, the two images may be formed ondifferent areas of the drum other than diametrically opposite ones asdisclosed herein. Moreover, the photoconductive surface was describedfor convenience of illustration as that being of a xerographic drum butthe invention may also employ other photosensitive members such asplates, webs and the like. Also the relative speed and length of thedielectric material and the photosensitive surface may be selected to beany desired magnitude other than as disclosed which would insure theimages on each member to effectively transfer on both sides of thesupport material. It is further within the scope of the invention tostore the first developed image on a stationary belt or surface whilethe second image is developed if so desired.

While the invention has been described with reference to a preferredembodiment it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the true spirit and scope of theinvention and, in addition, many modifications may be made to adapt aparticular situation or material to the teachings of the inventionwithout departing from the essential teachings.

What is claimed is:

1. Apparatus for obtaining right reading xerographic toner images onopposite sides of the support member comprising a continuous reusablephotosensitive surface supported for movement relative to charging,exposing and developing means for creating right and reverse readingtoner images on the photosensitive surface,

first electrostatic transfer means adjacent the photo sensitive surfacefor electrostatically transferring both right and reverse reading imagesfrom the photosensitive surface,

a single continuous, reusable storage surface adjacent saidphotosensitive surface for receiving only right reading imageselectrostatically transferred directly from the photosensitive surfaceby the first transfer 6 means and for storing the received image andrecycling it past the first transfer means simultaneously with thepassage of a reverse reading image on the photosensitive surface pastthe first transfer means, feed means for transporting a support memberbetween the photosensitive and storage surfaces to receive only reversereading images electrostatically transferred directly from thephotosensitive surface by the first transfer means and for preventingtransfer of the reverse images to the storage surface by the firsttransfer means,

second electrostatic transfer means adjacent the storage surface andsupport member receiving a reverse image at the first transfer means forelectrostatically transferring an image on the storage surface to thefree side of said support member,

whereby right reading toner images are obtained for opposite sides of asupport member.

2. The apparatus of claim 1 wherein the storage surface includes adielectric material.

3. The apparatus of claim 1 wherein the storage surface includes a belt.

4. The apparatus of claim 1 wherein the right and reverse reading tonerimages are formed on two areas on the photosensitive surface apredetermined distance apart.

5. The apparatus of claim 4 wherein the storage surface includes a beltof a length equal to said predetermined distance and adapted to be movedat the selected speed of the photosensitive surface whereby the storedimage lying on the belt returns to the first transfer means at the sametime a reverse reading image on the photosensitive surface moves pastthe first transfer means.

6. The apparatus of claim 1 further comprises fusing means to affix thetoner images transferred to the two surfaces of the support members toproduce a permanent duplex copy.

7. The apparatus of claim 1 wherein said photosensitive surface is on arigid cylindrical drum and said storage surface is on a flexibledielectric belt.

References Cited UNITED STATES PATENTS JOHN M. HORAN, Primary ExaminerUS. Cl. X.R. 355---26

